Uncertain decimal literal 0.03?3 loses its exact zero endpoint #785

Parsing 0.03?3 gives a positive lower endpoint instead of [0, 3/50]. I"0.03?3" gives the same bounds.

Version: IntervalArithmetic.jl 1.0.12, 8453a776432fbdde32a9edc3cb15da82eb9b3418, Julia 1.10.10 and 1.12.7, Linux 6.17.0-1020-oracle x86_64.

Both forms give these bounds on both Julia versions at default precision: Float64 endpoints, 256-bit BigFloat. Run in a fresh directory with Julia 1.10.10 on PATH:

git clone https://github.com/JuliaIntervals/IntervalArithmetic.jl.git
git -C IntervalArithmetic.jl checkout --detach 8453a776432fbdde32a9edc3cb15da82eb9b3418
julia --startup-file=no --project=env -e 'using Pkg; Pkg.develop(path="IntervalArithmetic.jl"); Pkg.add([PackageSpec(name="CRlibm", version="1.0.2"), PackageSpec(name="CoreMath", version="0.1.0"), PackageSpec(name="RoundingEmulator", version="0.2.1")])'
cat > repro.jl <<'JULIA'
# CC0-1.0
using IntervalArithmetic, Test

x = parse(Interval{Float64}, "0.03?3")
expected = (0.0, Float64(big(3)//50, RoundUp))
println("actual   ", bounds(x))
println("expected ", expected)
println("control  ", bounds(parse(Interval{Float64}, "[0,0.06]")))
@test bounds(x) == expected
JULIA
OPENBLAS_NUM_THREADS=1 julia -O3 --startup-file=no --threads=1 --project=env repro.jl

Actual: (2.698802673467014e-79, 0.060000000000000005). The assertion fails. Control: (0.0, 0.060000000000000005).

The parser contract requires tight enclosure and defines uncertainty in last-digit units. 3/100 ± 3/100 requires Float64 bounds (0.0, 0.060000000000000005).

The uncertain branch appears to round midpoint and decimal unit separately in BigFloat before subtracting and converting outward.

Related IEEE Std 1788-2015 clauses: 12.11.1, 12.11.3 (uncertain form (c)), 12.12.7. We rely on the package contract because the published IEEE body was unavailable.

Happy to send a PR.

— ChipLab